After getting knocked out of Friday’s start in San Francisco after allowing six runs, Max Scherzer sat in front of a screen and dissected footage of his delivery. For the first three-plus months of the season, Scherzer was arguably the best pitcher in baseball, possessing a 1.82 ERA, mountains of strikeouts and few walks.

But since July 7, Scherzer has pitched to a 5.05 ERA over eight starts. He has still struck out 55 batters, but also given up 11 home runs and walked nine after doing little of each much of the season. After another rough outing, this time against the Giants, Scherzer searched for the issue at the core of the inconsistency.

He found that his shoulder was dropping in his three-quarters delivery and his best pitch, his fastball, was flattening out. Normally, his fastball moves dramatically as it approaches the plate, barreling in late on right-handed batters.

Against the Giants, his fastball didn’t move as much as normal. Of the six extra-base hits Scherzer allowed, including two home runs, only one didn’t come on the fastball. Opponents are slugging .732 against his fastball this month compared to .388 or less in each of the previous four months.

“That’s kinda atypical when I give up damage,” he said after Friday’s game. “… It’s not a body mechanical thing. My legs and limbs are working in sync. It’s my arm action. It’s a small thing within my arm action where I’m not quite getting my fingers on top of the ball and it’s causing me to flatten everything out.”

Scherzer said he remembers going through this issue before, notably in 2010 with the Tigers and he was sent down to Class AAA Toledo once he figured it out. Scherzer said there several different drills he can use to get his arm in the right location.

“It’s going to take some work,” said Scherzer, who starts next on Thursday in Denver. “You just have to create a good habit with it. I’m going to have to throw a ball 10,000 times, between my next start, into a wall just to make sure I have this good habit. That’s what the reality of it is. This isn’t a huge fix, just a time-consuming fix.”

Scherzer said this issue is one that slowly crept up. At first, he said it was likely just a few times a game, then 10 times, then double that until it “found an inopportune time” against the Giants.

“Anytime I needed a glove side fastball, it was just flattening out and just running back over to the middle of the plate,” he said. “I just did that over and over and they made me pay. It’s not like I had bad [velocity] or anything is physically wrong.”

Scherzer knows his body and unique delivery well, and is meticulous about his preparation in between starts. He has fixed this glitch quickly before. And if the Nationals want to turn around their season, they will need their ace to pitch like he is capable of.

“It’s very frustrating because we need a win and it’s a bad time of the year to have a mechanical thing go wrong,” he said. “But at the same time, I think I can actually fix this and be ready within five days and be ready to go give the team a chance to win.”